1. Field of the Invention
This invention relates to sensing devices, and more particularly to a mechanical, temperature change sensing device, to be used in the manufacturing of fire alarms and the like.
2. Description of the Prior Art
Prior art sensing devices have in the past fit into essentially two categories, one being electrically energized sensing devices and the other being mechanically energized sensing devices. The electrically energized sensing devices of the prior art have one basic drawback, in that under some conditions an electrically activated sensing device may fail to sound an alarm because of an electrical power failure. Therefore, mechanical sensing devices are highly desirable since they operate completely independent of an electrical power source.
Mechanical sensing devices of the prior art include a number of devices which, although they are independent of an electrical source have a number of considerable disadvantages. For example, many of the prior art devices require that they be mounted in a particular orientation in order for them to function properly. Others contain a fuseing means, which when melted sound an alarm. This fuse, although quite reliable, has the disadvantage of being difficult to replace, and thus testing of the alarm system regularly becomes impractical. Another disadvantage of many of the prior art sensing devices is that they cannot be adjusted, or if they can, adjustment is difficult. Furthermore, many of the sensing devices of the prior art are only capable of sounding an alarm in the event of an increase in temperature, and thus application to a system which must be activated by a decrease in temperature is difficult. A further disadvantage of many of the mechanical prior art sensing devices is that they are simply too complicated, making them expensive to manufacture and buy.
The device of the present invention contemplates a novel mechanical sensing device which obviates many of the disadvantages encountered in the prior art devices. Unlike many of the prior art devices, the sensing device of the present invention is completely mechanical, can be mounted in any position and can be tested regularly without damaging or replacing any of the parts. Furthermore, the device of the present invention can be quickly and conveniently adjusted to sound an alarm at any temperature that may be required, whether this temperature be higher or lower than the prevailing atmospheric temperature.